PetroChina Company Limited
Thesis
Warren Buffett noted that when he first looked at PetroChina, he believed it was worth about $100 billion, but it was only selling for $35 billion at the time. This significant discount for one of the world’s largest oil companies caught his attention, leading him to invest with a margin of safety.
Did it work?
This is a long thesis premised on a large margin of safety (Buffett's $100B intrinsic value vs. $35B market price), but the stock has declined 94.1% since the pitch — a catastrophic loss for a long position. A decline of this magnitude decisively invalidates the undervaluation premise regardless of how much time has elapsed, as the market moved dramatically away from the claimed intrinsic value rather than converging toward it. Even under a multi-year horizon, a -94.1% return is far beyond normal interim noise.